MLB.com's Carrie Muskat has been covering Major League Baseball since 1981 and is the author of "Banks to Sandberg to Grace: Five Decades of Love and Frustration with the Cubs." You can follow her on Twitter @CarrieMuskat. Here, she blogs about the Cubs.

7/18 Mystery ball event Tuesday

If you’re coming to Tuesday’s Cubs game vs. the Astros, be prepared for a little mystery. Ryan Theriot and Cubs Charities have teamed up to create a “Mystery Ball” sale at Wrigley Field. Proceeds will benefit the National Wildlife Federation in support of its Gulf Coast relief efforts.

Sales will take place in front of the Wrigley Field gates, so even if you don’t have a ticket, you can still purchase a “Mystery Ball” or make a contribution.

Each Cubs player plus manager Lou Piniella plus “Mr. Cub” Ernie Banks and select Cubs alumni have autographed baseballs for the event. More than 1,000 baseballs will be sold. Each signed baseball will be placed in a brown bag and distributed randomly at the entrance gates. Fans can purchase a mystery ball for $20.

Fans may purchase the items when the gates open at 5:05 p.m. CT. Balls will be sold until the third inning or until supplies last.

Meta

The following are trademarks or service marks of Major League Baseball entities and may be used only with permission of Major League Baseball Properties, Inc. or the relevant Major League Baseball entity: Major League, Major League Baseball, MLB, the silhouetted batter logo, World Series, National League, American League, Division Series, League Championship Series, All-Star Game, and the names, nicknames, logos, uniform designs, color combinations, and slogans designating the Major League Baseball clubs and entities, and their respective mascots, events and exhibitions.